Seismic isolation systems, such as floors or plates designed to isolate equipment from sudden foundational shifts can be important in various applications. In particular, seismic base isolation systems are oftentimes powerful tools of earthquake engineering and often used to isolate non-structural contents of a building and/or sensitive equipment against sudden ground motions, which may be caused by a seismic event, such as earthquake, a natural event, a blast wave, etc. Typical applications for seismic isolation systems including buildings with high value assets, such as data centers, hospitals, museums, manufacturers with critical equipment, warehouses, laboratories and/or any application where it is important to protect critical assets. The goal of any seismic isolation system is to maximize safety, business continuity and preservation of irreplaceable items.
For example, U.S. patent application Ser. No. 13/578,868 discloses a seismic isolation device including a tabular base board having a plurality of curved convex protrusions formed thereon and a sliding plate having a sliding contact surface that is slidingly in contact with the plurality of curved convex protrusions and placed on a side of the convex protrusions of the base board, wherein the sliding contact surface of the sliding plate includes a plurality of high-friction portions arranged corresponding to the plurality of curved convex protrusions and enabling stable rest in a contact state with the plurality of the curved convex protrusions and a sliding surface other than the high-friction portions that has a lower apparent friction coefficient than the high-friction portions.
For another example, PCT Patent Application No. PCT/JP2012/006003 discloses a method for installing seismic isolation floor which comprises: a base disposition step in which a plurality of planar bases, each formed by arranging a plurality of upward convex curved surface portions on the upper surface thereof, are disposed on the upper surface of a floor by being installed on a plurality of lines of double-sided tape attached to the upper surface of the floor approximately parallel to each other; and a glide plate installation step in which a plurality of planar glide plates each having an approximately flat shaped lower surface are installed on the bases.
One challenge in designing a seismic isolation system of this type of construction is to construct a base plate having an appropriate coefficient of friction. Seismic isolation systems require low coefficients of kinetic and static friction so that when the ground or the foundational surface shakes, the supported body does not move. However, if the coefficient of static friction is too low, the supported body may easily move during regular use. The challenge in designing a seismic isolation system is to identify coefficients of static and kinetic friction that meet both needs.
The other challenge is to design a damping system for providing displacement control during a seismic event. While conventional damping systems usually require external curb or dampers to limit the movement of a seismic isolation system, the challenge is to design a damping system that uses internal chambers and dampers to save space.